Disk files are information storage devices which use at least one rotatable disk with concentric data tracks containing the information. Also included is a transducer for reading data from or writing data to various tracks on the rotatable disk. A head or transducer-positioning actuator connected to the head for moving it to the desired track and maintaining it over the track's central line during read or write operations is also included.
The transducer is attached to a slider which has an air-bearing surface. This surface rides on a cushion of air that is generated when the disk is rotating. The surface of the slider opposite to the air-bearing surface is attached to the suspension, and the suspension is attached to a support of the head-positioning actuator. A Pico-size slider may be 1.25 mm.times.1 mm.times.0.3 mm thick. The exact size of the Pico slider has not yet been firmly standardized. However, the examples given indicate the order of magnitude and it is clear that one has to deal with apparatus having extremely small dimensions.
The suspension provides dimensional stability between the slider and the actuator arm. It controls flexibility in pitch-and-roll motion of the slider relative to its direction of motion on the rotating disk. The suspension also provides resistance to yaw motion.
Typically, a suspension provides a load or force against the slider which is directed against the force of the air bearing between the slider's air-bearing surface and the disk surface. In this manner, the slider is maintained in extremely close proximity to--but out of contact with--the data surface of the disk.
Conventional suspensions typically are comprised of a load beam, which is mounted at one end to the actuator arm, and a flexure element or flexure which is attached to the other end of the load beam and supports the slider. The flexure element generally has a gimbal arrangement for permitting the slider to assume the respective different angular positions with respect to the data surface of the rotating disk.
The load beam provides the resilient spring action which biases the slider toward the surface of the disk, while (as noted above) the flexure provides flexibility for the slider as the slider rides on a cushion of air between the air-bearing surface and the rotating disk. Such a suspension is described in U.S. Pat. No. 4,167,765, assigned to the same assignee as the present application. A conventional slider is described in U.S. Pat. No. 3,823,416, also assigned to the same assignee as the present application.
The design of a suspension for a Pico-sized slider is particularly difficult due to the load gimbal stiffness, the size of the slider bonding pad, and the desire to utilize as much of the disk's real estate as possible. Furthermore, such a suspension must be robust so as to be able to withstand rough handling and shipping damage, among its other concerns. The gimbal design is also demanding because the required pitch-and-roll stiffness, including wires, have to be of the order of 60 mN-mm/Rad. A Nano-sized slider's requirements are twice or even three times higher.
The normal way of reducing stiffness is to make the gimbal features thinner, about 0.020 mm thick, and longer. This leads to fragility and because of the larger features, it also does not properly utilize the available disk's real estate areas. It is obvious that fragility is undesirable because it would be unable to withstand shock and handling damage. Furthermore, if a thin separate flexure is welded to the load beam, distortions can occur because of heat dissipation and clamping forces. Obviously, the handling of very small pieces may also pose additional difficulties.
An integral flexure approach has been developed which avoids these problems by using laminated suspensions. In the laminated suspensions, the electrical lead lines are integrated in the load beam so that the wiring issue is already taken care of. An integral flexure is a flexure that is a single piece with the load beam and not a separate part that is added to the load beam and welded thereto.
The laminated suspensions generally includes three layers, such as steel, insulating polyimide and copper. The electrical lead lines can be etched into the copper layer, while the polyimide layer can provide insulation. The steel layer can also be etched to provide strength characteristics for the suspension.
One of the problems in using the laminated suspensions of the above-noted type is the fact that such three-layer material is not well suited for a stamping/fabricating process. For example, in some suspensions it is also desirable to be able to stamp some formed portions, such as a pivoting dimple or flanges to provide rigidity to the overall suspension structure.
There are also other problems which arise when there is a need for unloading the suspension from the disk file for shipping or to avoid shock. For this purpose, a tab may be provided on the suspension so that the slider-suspension assembly can be moved outside the disk's real estate to prevent disk damage by the slider.